Toxicity of essential oil of Eugenia uniflora (L.) to Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae) and selectivity to the parasitoid Cleruchoides noackae (Lin & Hubert) (Hymenoptera: Mymaridae)

Abstract Thaumastocoris peregrinus Carpintero and Dellape, 2006 (Hemiptera: Thaumastocoridae) is an exotic insect that causes losses in the production of Eucalyptus sp. The egg parasitoid Cleruchoides noackae Lin and Huber, 2007 (Hymenoptera: Mymaridae) is the principal biological control agent of T. peregrinus. Essential oil, including Eugenia uniflora (L.) have a potential for managing this pest. The objective of this study was to evaluate the toxicity of E. uniflora to T. peregrinus and the selectivity of this oil on the parasitoid C. noackae and its parasitism on T. peregrinus. Toxicity of E. uniflora essential oil was tested at different concentrations to eggs, nymphs and adults of T. peregrinus. The selectivity of this oil was also evaluated in the pre- and post-parasitism of C. noackae on T. peregrinus eggs. The essential oil was analyzed by gas chromatography. Eugenia uniflora essential oil at 0.75% concentration showed insecticidal potential on T. peregrinus adults, nymphs and eggs, and was safer to C. noackae when applied one day after parasitism than pre-parasitism and 7-day post-parasitism. The major compounds found in the E. uniflora essential oil were calamen-10-one (20.20%), silfiperferol-6-em-5-one (10.06%), and germacrone (6.61%). Under laboratory conditions E. uniflora essential oil showed an insecticidal effect to different life stages of T. peregrinus, but it is selective for egg parasitoid C. noackae just one day after the parasitism occurs. Further studies should be carried out on eucalyptus plantations.